1. Field of the Invention
The present invention relates to image encoding and decoding, and more particularly, to an apparatus and a method for generating a coded block pattern (CBP) for an alpha channel image and an apparatus and a method for encoding or decoding the alpha channel image using the same.
2. Description of the Related Art
An alpha channel image has served as a mask to select a specific zone in a general image. In the ISO/IEC MPEG-4 standard, a method of encoding an image in object units is defined, wherein shape information is separately encoded to identify the image in object units. The shape information may be considered as the alpha channel image. However, in the MPEG-4 standard, since the shape information is encoded in a different way from a method of encoding general images, it is difficult to realize an apparatus for encoding an alpha channel image, and it is difficult to process the shape information in real time due to a significant amount of calculation.
According to the H.264/MPEG-4 pt.10 AVC standard technology (“Text of ISO/IEC FDIS 14496-10: Information Technology—Coding of audio-visual objects—Part 10: Advanced Video Coding”, ISO/IEC JTC 1/SC 29/WG 11, N5555, March, 2003), which has been developed by a Joint Video Team (JVT) of the ISO/IEC MPEG and ITU-T VCEG groups, general image encoding efficiency may be dramatically improved by performing spatial and temporal prediction encoding in various methods. In this standard technology, an enhanced function, integer transform coding, is used, and entropy coding efficiency is also improved using context adaptive binary arithmetic coding (CABAC). However, a method of processing an alpha channel image is not provided.